Method of manufacturing semiconductor device

ABSTRACT

The present technology provides a method of manufacturing a semiconductor device. The method includes forming a preliminary source structure, forming a stack structure on the preliminary source structure, the stack structure including a first material layer and a second material layer, forming a preliminary memory layer that penetrates the stack structure, forming a trench passing through the stack structure, forming a first buffer pattern by performing a surface treatment on a portion of the second material layer that is exposed by the trench, and forming a protective layer covering the first buffer pattern.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 17/090,735, filed on Nov. 5, 2020, and claimspriority under 35 U.S.C. § 119(a) to Korean patent application number10-2020-0068100 filed on Jun. 5, 2020, in the Korean IntellectualProperty Office, the entire disclosure of which is incorporated byreference herein.

BACKGROUND 1. Technical Field

The present disclosure relates to a method of manufacturing asemiconductor device, and more particularly, to a method ofmanufacturing a three-dimensional semiconductor device.

2. Related Art

A semiconductor device includes an integrated circuit configured of ametal oxide semiconductor field effect transistor (MOSFET). As the sizeand design rule of the semiconductor device are gradually reduced, thescaling down of the MOSFETs is also gradually accelerating.

However, the size reduction of the MOSFETs may cause a short channeleffect, or the like, resulting in a degradation of operationcharacteristics of the semiconductor device. Accordingly, variousmethods for forming a semiconductor device with better performance havebeen studied while overcoming the limitations due to high integration ofthe semiconductor device.

Furthermore, such an integrated circuit aims to increase the reliabilityof operations and to lower power consumption. Therefore, a method ofmanufacturing a device with higher reliability and lower powerconsumption in a smaller space is also being studied.

SUMMARY

A method of manufacturing a semiconductor device according to anembodiment of the present disclosure may include forming a preliminarysource structure, forming a stack structure on the preliminary sourcestructure, the stack structure including a first material layer and asecond material layer, forming a preliminary memory layer thatpenetrates the stack structure, forming a trench that penetrates thestack structure, forming a first buffer pattern by performing a surfacetreatment on a portion of the second material layer that is exposed bythe trench, and forming a protective layer covering the first bufferpattern.

A method of manufacturing a semiconductor device according to anembodiment of the present disclosure may include forming a preliminarysource structure, forming a stack structure on the preliminary sourcestructure, the stack structure including first material layers andsecond material layers, forming a preliminary memory layer thatpenetrates the stack structure, forming a trench that penetrates thestack structure, forming buffer patterns overlapping the first materiallayers, and forming a protective layer that covers the buffer patterns.

A method of manufacturing a semiconductor device according to anembodiment of the present disclosure may include forming a sourcesacrificial layer, forming a stack structure in which first materiallayers and second material layers are alternately stacked, forming achannel structure that penetrates the stack structure, forming a trenchthat penetrates the stack structure, forming buffer patterns byperforming a surface treatment on sidewalls of the first material layersthat are exposed by the trench, forming a protective layer that coversthe buffer patterns in the trench, forming a cavity by selectivelyremoving the source sacrificial layer, and forming a source layerconnected to the channel structure in the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view of a semiconductor device according to anembodiment of the present disclosure.

FIG. 1B is a cross-sectional view that is taken along a line A-A′ ofFIG. 1A.

FIGS. 2A to 2M are cross-sectional views for describing a method ofmanufacturing the semiconductor device according to on FIGS. 1A and 1B.

FIGS. 3A to 3K are cross-sectional views for describing a method ofmanufacturing a semiconductor device according to an embodiment of thepresent disclosure.

FIG. 4 is a block diagram, illustrating a configuration of a memorysystem, according to an embodiment of the present disclosure.

FIG. 5 is a block diagram, illustrating a configuration of a computingsystem, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Specific structural or functional descriptions of embodiments accordingto the concept which are disclosed in the present specification orapplication are illustrated only to describe the embodiments accordingto the concept of the present disclosure. The embodiments according tothe concept of the present disclosure may be carried out in variousforms and should not be construed as limited to the embodimentsdescribed in the present specification or application.

It will be understood that although the terms “first”, “second”, “third”etc. are used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another element. Thus, a first element in someembodiments could be termed a second element in other embodimentswithout departing from the teachings of the present disclosure.

Further, it will be understood that when an element is referred to asbeing “connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Embodiments of the present disclosure provides a method of manufacturinga semiconductor device that is capable of improving operationreliability.

FIG. 1A is a plan view of a semiconductor device according to anembodiment of the present disclosure. FIG. 1B is a cross-sectional viewthat is taken along a line A-A′ of FIG. 1A.

Referring to FIGS. 1A and 1B, the semiconductor device may include asource structure SOS. The source structure SOS may have a shape of aplate, extending along a plane that is defined by a first direction D1and a second direction D2. The first direction D1 and the seconddirection D2 may intersect each other. For example, the first directionD1 and the second direction D2 may be orthogonal to each other.

For example, the source structure SOS may be provided on a substratethat physically supports the source structure SOS. For example, thesubstrate may be a semiconductor substrate or an insulator substrate.

For example, a peripheral circuit structure with transistors and wiresbetween the source structure SOS and the substrate may be provided.

The source structure SOS may include a first source layer SL1, a secondsource layer SL2, and a third source layer SL3. The first source layerSL1, the second source layer SL2, and the third source layer SL3 may besequentially stacked in a third direction D3. The third direction D3 mayintersect the first direction D1 and the second direction D2. Forexample, the third direction D3 may be orthogonal to the first directionD1 and the second direction D2.

The first source layer SL1, the second source layer SL2, and the thirdsource layer SL3 may include the same material. The first source layerSL1, the second source layer SL2, and the third source layer SL3 mayinclude a semiconductor material. For example, the first source layerSL1, the second source layer SL2, and the third source layer SL3 mayinclude doped polysilicon.

A stack structure STA may be provided on the source structure SOS. Thestack structure STA may include conductive patterns CP and insulatinglayers IL that are alternately stacked in the third direction D3. Alowermost insulating layer IL of the stack structure STA may be providedon the third source layer SL3 of the source structure SOS, and theconductive patterns CP and the insulating layers IL may be alternatelystacked on the lowermost insulating layer IL.

The insulating layers IL may include an insulating material. Forexample, the insulating layers IL may include oxide. The conductivepattern CP may include a conductive layer. For example, the conductivelayer may include at least one of a doped silicon layer, a metalsilicide layer, tungsten, nickel, and cobalt. The conductive layer maybe used as a word line connected to a memory cell or a select lineconnected to a select transistor. The conductive pattern CP may furtherinclude a barrier layer covering a surface of the conductive layer. Thebarrier layer may be formed between the conductive layer and theinsulating layer IL. For example, the barrier layer may include at leastone of titanium nitride and tantalum nitride.

Channel structures CS, passing through the stack structure STA, thethird source layer SL3, and the second source layer SL2, may beprovided. The channel structures CS may pass through the insulatinglayers IL and the conductive patterns CP of the stack structure STA. Thechannel structures CS may extend in the third direction D3. A lowermostportion of the channel structure CS may be provided in the first sourcelayer SL1. The channel structure CS may be electrically connected to thesecond source layer SL2 of the source structure SOS.

Each of the channel structures CS may include a filling layer FI and achannel layer CL that surround the filling layer FI. The filling layerFI and the channel layer CL may pass through the stack structure STA,the third source layer SL3, and the second source layer L2. The fillinglayer FI and the channel layer CL may extend in the third direction D3.The channel layer CL may contact the second source layer SL2. Thechannel layer CL may be electrically connected to the second sourcelayer SL2 of the source structure SOS.

The filling layer FI may include an insulating material. For example,the filling layer FI may include oxide. The channel layer CL may includea semiconductor material. For example, the channel layer CL may includepolysilicon.

A first memory layer ML1 and a second memory layer ML2 that surround thechannel structure CS may be provided. The first memory layer ML1 maysurround an upper portion and a middle portion of the channel structureCS. The second memory layer ML2 may surround a lower portion of thechannel structure CS. The first memory layer ML1 may pass through thestack structure STA and the third source layer SL3. The second memorylayer ML2 may be provided in the first source layer SL1.

The first and second memory layers ML1 and ML2 may be spaced apart fromeach other in the third direction D3. A portion of the second sourcelayer SL2 may be provided between the first memory layer ML1 and thesecond memory layer ML2. The portion of the second source layer SL2 maycontact the channel layer CL. The first and second memory layers ML1 andML2 may be spaced apart from each other by the second source layer SL2.

The first memory layer ML1 may include a first tunnel insulating layerTL1 that surrounds an upper portion and a middle portion of the channellayer CL, a first data storage layer DL1 that surrounds the first tunnelinsulating layer TL1, and a first blocking layer BKL1 that surrounds thefirst data storage layer DL1. The second memory layer ML2 may include asecond tunnel insulating layer TL2 that surrounds a lower portion of thechannel layer CL, a second data storage layer DL2 that surrounds thesecond tunnel insulating layer TL2, and a second blocking layer BKL2that surrounds the second data storage layer DL2.

The first tunnel insulating layer TL1 and the second tunnel insulatinglayer TL2 may be spaced apart from each other in the third direction D3.A portion of the second source layer SL2 may be provided between thefirst tunnel insulating layer TL1 and the second tunnel insulating layerTL2. The first data storage layer DL1 and the second data storage layerDL2 may be spaced apart from each other in the third direction D3. Aportion of the second source layer SL2 may be provided between the firstdata storage layer DL1 and the second data storage layer DL2. The firstblocking layer BKL1 and the second blocking layer BKL2 may be spacedapart from each other in the third direction D3. A portion of the secondsource layer SL2 may be provided between the first blocking layer BKL1and the second blocking layer BKL2.

The first and second tunnel insulating layers TL1 and TL2 may include amaterial that is capable of charge tunneling. For example, the first andsecond tunnel insulating layers TL1 and TL2 may include oxide. Forexample, the first and second data storage layers DL1 and DL2 mayinclude nitride to which charges may be trapped. A material that isincluded in the first and second data storage layers DL1 and DL2 is notlimited to nitride and may be variously modified based on a data storagemethod. For example, the first and second data storage layers DL1 andDL2 may include silicon, a phase change material, or nanodot. The firstand second blocking layers BKL1 and BKL2 may include a material that iscapable of blocking the movement of a charge. For example, the first andsecond blocking layers BKL1 and BKL2 may include oxide.

A slit structure SLS, passing through the stack structure STA, the thirdsource layer SL3, and the second source layer SL2, may be provided. Theslit structure SLS may extend in the second direction D2 and the thirddirection D3. The slit structure SLS may extend in the third directionD3 and may pass through the stack structure STA, the third source layerSL3, and the second source layer SL2. The lowermost portion of the slitstructure SLS may be disposed in the first source layer SL1.

The slit structure SLS may include spacers SP and a source contact SC.The spacers SP may be disposed on both sides of the source contact SC.The spacers SP and the source contact SC may extend in the seconddirection D2 and the third direction D3. The spacers SP and the sourcecontact SC may extend in the third direction D3 and may pass through thestack structure STA, the third source layer SL3, and the second sourcelayer SL2.

The spacers SP may be spaced apart from each other in the firstdirection D1 with the source contact SC positioned therebetween. Thesource contact SC may be spaced apart from the stack structure STA, thethird source layer SL3, and the second source layer SL2 by the spacersSP. The source contact SC may contact the first source layer SL1 of thesource structure SOS. The lowermost portion of the source contact SC maybe disposed in the first source layer SL1. The source contact SC may beelectrically connected to the first source layer SL1 of the sourcestructure SOS. The source contact SC may be electrically separated fromthe conductive pattern CP by the spacer SP.

The spacer SP may include an insulating material. For example, thespacer SP may include oxide. The source contact SC may include aconductive material. For example, the source contact SC may include atleast one of polysilicon and tungsten.

The semiconductor device may have a width that is relatively small inthe first direction D1 of the slit structure SLS. Accordingly, adistance L in the first direction D1 between the centers of two slitstructures SLS that are adjacent to each other may be relatively small,and the degree of integration of the semiconductor device may beimproved.

FIGS. 2A to 2M are cross-sectional views for describing a method ofmanufacturing the semiconductor device according to FIGS. 1A and 1B.

For brevity of description, the same reference numerals are used for thecomponents that are described with reference to FIGS. 1A and 1B, andrepetitive description will be omitted.

The manufacturing method, described below, is merely one embodiment ofthe method of manufacturing the semiconductor memory device according toFIGS. 1A and 1B, and the method of manufacturing the semiconductormemory device, according to FIGS. 1A and 1B, is not limited to themanufacturing method described below.

Referring to FIG. 2A, a preliminary source structure pSOS may be formed.The preliminary source structure pSOS may include a first source layerSL1, a first source protective layer SPL1, a source sacrificial layerSFL, a second source protective layer SPL2, and the third source layerSL3, which are sequentially stacked in the third direction D3. The firstsource layer SL1, the first source protective layer SPL1, the sourcesacrificial layer SFL, the second source protective layer SPL2, and thethird source layer SL3 may be sequentially formed to form thepreliminary source structure pSOS. The first and second sourceprotective layers SPL1 and SPL2 may be disposed between the first andthird source layers SL1 and SL3, and the source sacrificial layer SFLmay be disposed between the first and second source protective layersSPL1 and SPL2.

The source sacrificial layer SFL may include a semiconductor material.For example, the source sacrificial layer SFL may include polysilicon.The first and second source protective layers SPL1 and SPL2 may includea material with an etching selectivity with respect to the first andthird source layers SL1 and SL3 and the source sacrificial layer SFL.For example, the first and second source protective layers SPL1 and SPL2may include oxide.

The stack structure STA may be formed on the preliminary sourcestructure pSOS. The stack structure STA may include insulating layers ILand sacrificial layers FL. The insulating layers IL may be defined asfirst material layers. The sacrificial layers FL may be defined assecond material layers. The insulating layers IL and the sacrificiallayers FL may be alternately stacked in the third direction D3. Thestack structure STA may be formed by forming the lowermost insulatinglayer IL of the stack structure STA on the preliminary source structurepSOS and alternately forming the sacrificial layers FL and theinsulating layers IL on the lowermost insulating layer IL. Thesacrificial layers FL may include a material that is different from thatof the insulating layers IL. For example, the sacrificial layers FL mayinclude nitride.

Referring to FIG. 2B, the channel structures CS and preliminary memorylayers pML may be formed. The channel structure CS may pass through thestack structure STA, the third source layer SL3, the second sourceprotective layer SPL2, the source sacrificial layer SFL, and the firstsource protective layer SPL1. The channel structure CS may extend in thethird direction D3. The lowermost portion of the channel structure CSmay be disposed in the first source layer SL1. The preliminary memorylayer pML may surround the channel structure CS. The preliminary memorylayer pML may pass through the stack structure STA, the third sourcelayer SL3, the second source protective layer SPL2, the sourcesacrificial layer SFL, and the first source protective layer SPL1. Thepreliminary memory layer pML may extend in the third direction D3. Thelowermost portion of the preliminary memory layer pML may be disposed inthe first source layer SL1.

The channel structure CS may include the channel layer CL and thefilling layer FI in the channel layer CL. The preliminary memory layerpML may include a preliminary tunnel insulating layer pTL that surroundsthe channel structure CS, a preliminary data storage layer pDL thatsurrounds the preliminary tunnel insulating layer pTL, and a preliminaryblocking layer pBKL that surrounds the preliminary data storage layerpDL.

The forming of the channel structure CS and the preliminary memory layerpML may include forming a first hole HO1 that passes through the stackstructure STA, the third source layer SL3, the second source protectivelayer SPL2, the source sacrificial layer SFL, and the first sourceprotective layer SPL1, and sequentially forming the preliminary blockinglayer pBKL, the preliminary data storage layer pDL, the preliminarytunnel insulating layer pTL, the channel layer CL, and the filling layerFI in the first hole HO1.

The preliminary tunnel insulating layer pTL may include a material thatis capable of charge tunneling. The preliminary data storage layer pDLmay include a material to which a charge may be trapped. The preliminaryblocking layer pBKL may include a material that is capable of blocking amovement of a charge.

Referring to FIG. 2C, a first trench TR1 that passes through the stackstructure STA and the third source layer SL3 may be formed. The firsttrench TR1 may extend in the second direction D2 and the third directionD3. The first trench TR1 may be formed between the channel structuresCS.

The insulating layers IL, the sacrificial layers FL, and the thirdsource layer SL3 may be exposed based on the formation of the firsttrench TR1. The sidewalls of the insulating layers IL that are exposedbased on the formation of the first trench TR1 may be defined as firstsidewalls SW1. The sidewalls of the sacrificial layers FL that areexposed based on the formation of the first trench TR1 may be defined assecond sidewalls SW2. A sidewall of the third source layer SL3 that isexposed based on the formation of the first trench TR1 may be defined asa third sidewall SW3. An upper surface of the second source protectivelayer SPL2 may be exposed because the first trench TR1 is formed. Thefirst trench TR1 may be defined by the first sidewalls SW1 of theinsulating layers IL, the second sidewalls SW2 of the sacrificial layersFL, the third sidewall SW3 of the third source layer SL3, and the uppersurface of the second source protective layer SPL2.

The center of the first trench TR1 may be defined by a first center lineC1-C1′. The first center line C1-C1′ may be a virtual line thatdelineates the center of the first trench TR1 in the first direction D1.In other words, the first center line C1-C1′ may indicate the center ofthe first trench TR1 in the first direction D1.

Referring to FIG. 2D, a surface treatment may be performed on thesacrificial layers FL and the third source layer SL3 that are exposed bythe first trench TR1. A surface treatment may be performed on the secondmaterial layers of the stack structure STA. For example, the surfacetreatment may be an oxidation process, and the portions of thesacrificial layers FL and the third source layer SL3 that are exposedafter the formation of the first trench TR1 may be oxidized. A surfacetreatment may be performed on a portion of the third source layer SL3that is exposed by the first trench TR1 to form a first buffer patternBP1. A surface treatment may be performed on a portion that is adjacentto the third sidewall SW3 (refer to FIG. 2C) of the third source layerSL3 to form the first buffer pattern BP1. A surface treatment may beperformed on a portion of the third source layer SL3, and thus, theportion of the third source layer SL3 may become the first bufferpattern BP1.

The portion of the third source layer SL3 may extend to the center ofthe first trench TR1 while changing into the first buffer pattern BP1 byperforming the surface treatment on the portion of the third sourcelayer SL3. A portion of the first buffer pattern BP1 may be disposedbetween the insulating layer IL and the second source protective layerSPL2. A lower surface of the first buffer pattern BP1 may contact anupper surface of the second source protective layer SPL2, and an uppersurface of the first buffer pattern BP1 may contact a lower surface ofthe insulating layer IL. The first buffer pattern BP1 may include thesame material as the insulating layer IL. For example, the first bufferpatterns BP1 may include oxide.

A surface treatment may be performed on a portion of the sacrificiallayer FL that is exposed by the first trench TR1 to form a second bufferpattern BP2. A surface treatment may be performed on a portion that isadjacent to the second sidewall SW2 (refer to FIG. 2C) of thesacrificial layer FL to form the second buffer pattern BP2. A portion ofthe sacrificial layer FL may be changed into the second buffer patternBP2. The second buffer patterns BP2 may be disposed between theinsulating layers IL. The second buffer patterns BP2 may overlap theinsulating layers IL. For example, the second buffer patterns BP2 mayvertically overlap the insulating layers IL.

The portion of the sacrificial layer FL may extend to the center of thefirst trench TR1 while changing into the second buffer pattern BP2 byperforming the surface treatment on the portion of the sacrificial layerFL. A portion of the second buffer pattern BP2 may be disposed betweenthe insulating layers IL. The portion of the second buffer pattern BP2may overlap the insulating layers IL. For example, the portion of thesecond buffer pattern BP2 may vertically overlap the insulating layersIL. A lower surface of the second buffer pattern BP2 may contact anupper surface of the insulating layer IL. An upper surface of the secondbuffer pattern BP2 may contact the lower surface of the insulating layerIL. The second buffer pattern BP2 may include the same material as theinsulating layer IL. For example, the second buffer patterns BP2 mayinclude oxide.

A sidewall of the sacrificial layer FL that contacts the second bufferpattern BP2 may be defined as a fourth sidewall SW4, and a sidewall ofthe second buffer pattern BP2 that is adjacent to a first center lineC1-C1′ may be defined as a fifth sidewall SW5. A sidewall of the thirdsource layer SL3 that contacts the first buffer pattern BP1 may bedefined as a sixth sidewall SW6, and a sidewall of the first bufferpattern BP1 that is adjacent to the first center line C1-C1′ may bedefined as a seventh sidewall SW7.

The distance between the first sidewall SW1 of the insulating layer ILand the first center line C1-C1′ may be defined as a first distance L1.The distance between the fourth sidewall SW4 of the sacrificial layer FLand the first center line C1-C1′ may be defined as a second distance L2.The distance between the fifth sidewall SW5 of the second buffer patternBP2 and the first center line C1-C1′ may be defined as a third distanceL3. The distance between the sixth sidewall SW6 of the third sourcelayer SL3 and the first center line C1-C1′ may be defined as a fourthdistance L4. The distance between the seventh sidewall SW7 of the firstbuffer pattern BP1 and the first center line C1-C1′ may be defined as afifth distance L5.

The third distance L3 and the fifth distance L5 may be less than thefirst distance L1. In other words, the shortest distance between thefirst buffer pattern BP1 and the center of the first trench TR1 and theshortest distance between the second buffer pattern BP2 and the centerof the first trench TR1 may be less than the shortest distance betweenthe insulating layer IL and the center of the first trench TR1.

The second distance L2 and the fourth distance L4 may be greater thanthe first distance L1. In other words, the shortest distance between thesacrificial layer FL and the center of the first trench TR1 and theshortest distance between the third source layer SL3 and the center ofthe first trench TR1 may be greater than the shortest distance betweenthe insulating layer IL and the center of the first trench TR1.

Referring to FIG. 2E, a first protective layer PL1 may be formed in thefirst trench TR1. The first protective layer PL1 may cover theinsulating layers IL, the first buffer patterns BP1, the second bufferpatterns BP2, and the second source protective layer SPL2. The firstprotective layer PL1 may cover the first sidewalls SW1 of the insulatinglayers IL, the seventh sidewalls SW7 of the first buffer patterns BP1,the fifth sidewalls SW5 of the second buffer patterns BP2, and the uppersurface of the second source protective layer SPL2.

The first protective layer PL1 may be conformally formed on the firstsidewalls SW1 of the insulating layers IL, the seventh sidewalls SW7 ofthe first buffer patterns BP1, and the fifth sidewalls SW5 of the secondbuffer patterns BP2, and thus, an inner sidewall of the first protectivelayer PL1 may include a portion that is relatively close to the firstcenter line C1-C1′ and a portion that is relatively distant from thefirst center line C1-C1′. In other words, a distance between the innersidewall of the first protective layer PL1 and the first center lineC1-C1′ might not be uniform.

The first protective layer PL1 may include an interposed portion PL1 aand a recess PL1 b. The interposed portion PL1 a of the first protectivelayer PL1 may be disposed between the second buffer patterns BP2. Anupper surface of the interposed portion PL1 a of the first protectivelayer PL1 may contact the lower surface of the second buffer patternBP2. A lower surface of the interposed portion PL1 a of the firstprotective layer PL1 may contact the upper surface of the second bufferpattern BP2. The recess PL1 b of the first protective layer PL1 may beformed by recessing the inner sidewall of the first protective layer PL1toward the interposed portion PL1 a of the first protective layer PL1and the insulating layer IL. The recess PL1 b of the first protectivelayer PL1 may be formed at the same level as the interposed portion PL1a of the first protective layer PL1 and the insulating layer IL.

The first protective layer PL1 may be a single layer. In other words,the first protective layer PL1 may be configured of one material. Thefirst protective layer PL1 may include a material that may be etchedsimultaneously with the preliminary data storage layer pDL. For example,the first protective layer PL1 may include the same material as thepreliminary data storage layer pDL. For example, the first protectivelayer PL1 may include nitride.

Referring to FIG. 2F, a portion of a lower portion of the firstprotective layer PL1, a portion of the second source protective layerSPL2, and a portion of the source sacrificial layer SFL may be removedthrough the first trench TR1. Accordingly, the first trench TR1 may beexpanded. The first trench TR1 may be expanded and may pass through thesecond source protective layer SPL2.

The first trench TR1 may be expanded, and a lowermost portion of thefirst trench TR1 may be disposed in the source sacrificial layer SFL.The source sacrificial layer SFL may be exposed by the first trench TR1.While the first trench TR1 is expanded, the first protective layer PL1may protect the first buffer patterns BP1, the second buffer patternsBP2, and the insulating layer IL.

Referring to FIG. 2G, the source sacrificial layer SFL (refer to FIG.2F) may be removed. The removing of the source sacrificial layer SFL mayinclude inserting a material that is capable of etching the sourcesacrificial layer SFL through the first trench TR1. While the sourcesacrificial layer SFL is being removed, the first protective layer PL1may protect the first buffer patterns BP1, the second buffer patternsBP2, and the insulating layer IL. While the source sacrificial layer SFLis being removed, the first and second source protective layers SPL1 andSPL2 might not be etched.

The source sacrificial layer SFL may be removed, and thus, a firstcavity CA1 may be formed. An empty space that is formed by removing thesource sacrificial layer SFL may be defined as the first cavity CA1. Thefirst cavity CA1 may be an empty space between the first and secondsource protective layers SPL1 and SPL2.

The source sacrificial layer SFL, which is a portion of the preliminarysource structure pSOS, may be removed, and thus, a portion of thepreliminary blocking layer pBKL of the preliminary memory layer pML maybe exposed. The source sacrificial layer SFL may be removed, and thus,an upper surface of the first source protective layer SPL1 and a lowersurface of the second source protective layer SPL2 may be exposed.

Referring to FIG. 2H, the portion of the preliminary blocking layer pBKL(refer to FIG. 2G) that is exposed by the first cavity CA1 may beremoved. The portion of the preliminary blocking layer pBKL may beremoved, and thus, the preliminary blocking layer pBKL may be dividedinto a first blocking layer BKL1 and a second blocking layer BKL2. Thefirst blocking layer BKL1 and the second blocking layer BKL2 may bespaced apart from each other in the third direction D3. The portion ofthe preliminary blocking layer pBKL may be removed, and thus, the firstcavity CA1 may be expanded, and a portion of the preliminary datastorage layer pDL may be exposed.

The first and second source protective layers SPL1 and SPL2 (refer toFIG. 2G) may be removed while removing the portion of the preliminaryblocking layer pBKL or through a separate process. For example, when theportion of the preliminary blocking layer pBKL and the first and secondsource protective layers SPL1 and SPL2 are simultaneously removed, theportion of the preliminary blocking layer pBKL and the first and secondsource protective layers SPL1 and SPL2 may be simultaneously removed bya first etching material that is inserted into the first trench TR1 andthe first cavity CA1. The first etching material may be a material thatis capable of etching the preliminary blocking layer pBKL and the firstand second source protective layers SPL1 and SPL2.

While the portion of the preliminary blocking layer pBKL and the firstand second source protective layers SPL1 and SPL2 are being removed, thefirst protective layer PL1 may protect the first buffer patterns BP1,the second buffer patterns BP2, and the insulating layer IL.

Referring to FIG. 2I, the portion of the preliminary data storage layerpDL (refer to FIG. 2H) that is exposed by the first cavity CA1 may beremoved. The portion of the preliminary data storage layer pDL may beremoved, and thus, the preliminary data storage layer pDL may be dividedinto a first data storage layer DL1 and a second data storage layer DL2.The first data storage layer DL1 and the second data storage layer DL2may be spaced apart from each other in the third direction D3. Theportion of the preliminary data storage layer pDL may be removed, andthus, the first cavity CA1 may be expanded and a portion of thepreliminary tunnel insulating layer pTL may be exposed.

The first protective layer PL1 (refer to FIG. 2H) may be removed whileremoving the portion of the preliminary data storage layer pDL orthrough a separate process. For example, when the portion of thepreliminary data storage layer pDL and the first protective layer PL1are simultaneously removed, the portion of the preliminary data storagelayer pDL and the first protective layer PL1 may be simultaneouslyremoved by a second etching material that is inserted into the firsttrench TR1 and the first cavity CA1. The second etching material may bea material that is capable of etching the preliminary data storage layerpDL and the first protective layer PL1. The first protective layer PL1may be removed, and thus, the insulating layers IL, the first bufferpatterns BP1, and the second buffer patterns BP2 may be exposed.

Referring to FIG. 2J, the portion of the preliminary tunnel insulatinglayer pTL (refer to FIG. 2I) that is exposed by the first cavity CA1 maybe removed. The portion of the preliminary tunnel insulating layer pTLmay be removed, and thus, the preliminary tunnel insulating layer pTLmay be divided into a first tunnel insulating layer TL1 and a secondtunnel insulating layer TL2. The first tunnel insulating layer TL1 andthe second tunnel insulating layer TL2 may be spaced apart from eachother in the third direction D3. The portion of the preliminary tunnelinsulating layer pTL may be removed, and thus, the first cavity CA1 maybe expanded, and a portion of the channel layer CL may be exposed.

The first buffer pattern BP1, the second buffer pattern BP2, and aportion the insulating layer IL may be removed while removing theportion of the preliminary tunnel insulating layer pTL. For example, theportion of the preliminary tunnel insulating layer pTL, the first bufferpattern BP1, the second buffer pattern BP2, and the portion of theinsulating layer IL may be removed by a third etching material that isinserted into the first trench TR1 and the first capacity CA1. The thirdetching material may include a material that is capable of etching thepreliminary tunnel insulating layer pTL, the first buffer pattern BP1,the second buffer pattern BP2, and the insulating layer IL.

The first buffer pattern BP1 may be removed, and thus, the sidewall ofthe third source layer SL3 may be exposed. The second buffer pattern BP2may be removed, and thus, the sidewall of the sacrificial layer FL maybe exposed.

The portion of the insulating layer IL may be removed, and thus, aneighth sidewall SW8 of the insulating layer IL that is exposed by thefirst trench TR1 may be defined. The second buffer pattern BP2 may beremoved, and thus, a ninth sidewall SW9 of the sacrificial layer FL thatis exposed by the first trench TR1 may be defined. The first bufferpattern BP1 may be removed, and thus, a tenth sidewall SW10 of the thirdsource layer SL3 that is exposed by the first trench TR1 may be defined.

The distance between the ninth sidewall SW9 and the first center lineC1-C1′ and the distance between the tenth sidewall SW10 and the firstcenter line C1-C1′ may be the same. The distance between the eighthsidewall SW8 and the first centerline C1-C1′ may be greater than thedistance between the ninth and tenth sidewalls SW9 and SW10 and thefirst centerline C1-C1′.

Referring to FIG. 2K, a preliminary source layer pSL may be formed inthe first cavity CA1 and the first trench TR1. The preliminary sourcelayer pSL may fill a portion of the first cavity CA1 and a portion ofthe first trench TR1. The preliminary source layer pSL may cover anupper surface of the first source layer SL1, a lower surface of thethird source layer SL3, the tenth sidewall SW10 of the third sourcelayer SL3, the ninth sidewall SW9 of the sacrificial layer FL, and theeighth sidewall SW8 of the insulating layer IL. The preliminary sourcelayer pSL may contact the channel layer CL of the channel structure CS.The preliminary source layer pSL may include a semiconductor material.For example, the preliminary source layer pSL may include polysilicon.

Referring to FIG. 2L, a portion of the preliminary source layer pSL(refer to FIG. 2K) may be removed. The portion that covers the tenthsidewall SW10 (refer to FIG. 2K) of the third source layer SL3 of thepreliminary source layer pSL, the ninth sidewall SW9 of the sacrificiallayer FL, and the eighth sidewall SW8 of the insulating layer IL may beremoved. A portion that is formed in the first trench TR1 of thepreliminary source layer pSL may be removed. The preliminary sourcelayer pSL from which the portion is removed may be defined as the secondsource layer SL2. A portion of the third source layer SL3 may be removedtogether with a portion of the preliminary source layer pSL.

As the portion of the preliminary source layer pSL is removed, the firsttrench TR1 may be opened and the sacrificial layers FL and theinsulating layers IL may be exposed again. As the portion of thepreliminary source layer pSL is removed, a second cavity CA2 may beformed in the source structure SOS. The second cavity CA2 may be anempty space that is surrounded by the second source layer SL2. Thesecond cavity CA2 may be connected to the first trench TR1.

Referring to FIG. 2M, the sacrificial layers FL (refer to FIG. 2L) maybe replaced with the conductive patterns CP. The replacing of thesacrificial layers FL with the conductive patterns CP may includeremoving the sacrificial layers FL that are exposed through the firsttrench TR1 and forming the conductive patterns CP.

Subsequently, the spacers SP may be formed in the first trench TR1 andthe second cavity CA2. The forming of the spacers SP may includeconformally forming a spacer layer in the first trench TR1 and thesecond cavity CA2 and removing a lower portion of the spacer layerthrough an anisotropic etching process. For example, a portion of thefirst source layer SL1 may be removed together with the lower portion ofthe spacer layer. The first source layer SL1 may be exposed between thespacers SP.

Subsequently, the source contact SC (refer to FIG. 1B) may be formedbetween the spacers SP.

In the method of manufacturing the semiconductor device, the firstprotective layer PL1 may protect the insulating layer IL of the stackstructure STA and the second buffer pattern BP2 in a process of removingthe source sacrificial layer SFL and removing a portion of thepreliminary blocking layer pBKL. In addition, in a process of removing aportion of the preliminary data storage layer pDL, the second bufferpattern BP2 may protect the sacrificial layer FL of the stack structureSTA. The first protective layer PL1 may be removed together in a processof removing the portion of the preliminary data storage layer pDL.

Accordingly, the preliminary source layer pSL may be formed in a statein which there is no separate layer that covers the sidewalls of theinsulating layer IL and the sacrificial layer FL of the stack structureSTA, and thus, the width of the first trench TR1 may be designed to berelatively small. As the width of the first trench TR1 is designed to berelatively small, the degree of integration of the semiconductor devicemay be improved.

In addition, as the second cavity CA2 is formed in a state in whichthere is no separate layer that covers the sidewalls of the insulatinglayer IL and the sacrificial layer FL of the stack structure STA, anover verify fail (OVF) based on the formation of the second cavity CA2may be prevented.

FIGS. 3A to 3K are cross-sectional views for describing a method ofmanufacturing a semiconductor device according to an embodiment of thepresent disclosure.

The method of manufacturing the semiconductor device according to FIGS.3A to 3K may be similar to the method of manufacturing the semiconductordevice according to FIGS. 2A to 2M, except as described below.

Referring to FIG. 3A, similarly to that described with reference toFIGS. 2A to 2C, the preliminary source structure pSOS, the stackstructure STA, the preliminary memory layer pML, the channel structureCS, and the first trench TR1 may be formed. The insulating layers IL ofthe stack structure STA may be defined as first material layers, and thesacrificial layers FL of the stack structure STA may be defined assecond material layers.

Subsequently, a surface treatment may be performed on the insulatinglayers IL that are exposed by the first trench TR1. A surface treatmentmay be performed on the first material layers of the stack structureSTA. For example, the surface treatment may be a nitriding process, andthe insulating layers IL that are exposed by the first trench TR1 may benitrided. A surface treatment may be performed on a portion of theinsulating layer IL that is exposed by the first trench TR1 to form athird buffer pattern BP3. A portion of the insulating layer IL may bechanged to a third buffer pattern BP3. The third buffer patterns BP3 maybe disposed between the sacrificial layers FL. The third buffer patternsBP3 may overlap the sacrificial layers FL. The third buffer pattern BP3may include the same material as the sacrificial layer FL. For example,the third buffer pattern BP3 may include nitride.

Referring to FIG. 3B, a second protective layer PL2 may be formed in thefirst trench TR1. The second protective layer PL2 may cover thesacrificial layers FL, the third buffer patterns BP3, the third sourcelayer SL3, and the second source protective layer SPL2. The secondprotective layer PL2 may include portions that are interposed betweenthe third buffer patterns BP3.

The second protective layer PL2 may have multiple layers. The secondprotective layer PL2 may include a first protective portion PL2 a and asecond protective portion PL2 b. The first protective portion PL2 a maybe a layer that covers the sacrificial layers FL, the third bufferpatterns BP3, the third source layer SL3, and the second sourceprotective layer SPL2. The second protective portion PL2 b may be alayer that covers the first protective portion PL2 a. The first andsecond protective portions PL2 a and PL2 b may include differentmaterials. The first protective portion PL2 a may include the samematerial as the insulating layer IL. The second protective portion PL2 bmay include the same material as the sacrificial layer FL. For example,the first protective portion PL2 a may include oxide, and the secondprotective portion PL2 b may include nitride.

Referring to FIG. 3C, a lower portion of the second protective layerPL2, a portion of the second source protective layer SPL2, and a portionof the source sacrificial layer SFL may be removed through the firsttrench TR1. While the portion of the second source protective layer SPL2and the portion of the source sacrificial layer SFL are being removed,the second protective layer PL2 may protect the third buffer patternsBP3 and the sacrificial layers FL.

Referring to FIG. 3D, the source sacrificial layer SFL (refer to FIG.3C) may be removed. While the source sacrificial layer SFL is beingremoved, the second protective layer PL2 may protect the third bufferpatterns BP3, the sacrificial layers FL, and the third source layer SL3.While the source sacrificial layer SFL is being removed, the first andsecond source protective layers SPL1 and SPL2 might not be etched. Thesource sacrificial layer SFL may be removed, and thus, the first cavityCA1 may be formed. The source sacrificial layer SFL may be removed, andthus, a portion of the preliminary blocking layer pBKL of thepreliminary memory layer pML may be exposed.

Referring to FIG. 3E, the portion of the preliminary blocking layer pBKL(refer to FIG. 3D) that is exposed by the first cavity CA1 may beremoved. The portion of the preliminary blocking layer pBKL may beremoved, and thus, the preliminary blocking layer pBKL may be dividedinto a first blocking layer BKL1 and a second blocking layer BKL2. Theportion of the preliminary blocking layer pBKL may be removed, and thus,a portion of the preliminary data storage layer pDL may be exposed.

The first and second source protective layers SPL1 and SPL2 (refer toFIG. 3D) may be removed simultaneously with removing the portion of thepreliminary blocking layer pBKL or through a separate process.

While the portion of the preliminary blocking layer pBKL and the firstand second source protective layers SPL1 and SPL2 are being removed, thesecond protective layer PL2 may protect the third buffer patterns BP3,the sacrificial layers FL, and the third source layer SL3.

Referring to FIG. 3F, the portion of the preliminary data storage layerpDL (refer to FIG. 3E) that is exposed by the first cavity CA1 may beremoved. The portion of the preliminary data storage layer pDL may beremoved, and thus, the preliminary data storage layer pDL may be dividedinto a first data storage layer DL1 and a second data storage layer DL2.The portion of the preliminary data storage layer pDL may be removed,and thus, a portion of the preliminary tunnel insulating layer pTL maybe exposed.

The second protective portion PL2 b (refer to FIG. 3E) of the secondprotective layer PL2 (refer to FIG. 3E) may be removed simultaneouslywith removing the portion of the preliminary data storage layer pDL orthrough a separate process. For example, when the portion of thepreliminary data storage layer pDL and the second protective portion PL2b are simultaneously removed, the portion of the preliminary datastorage layer pDL and the second protective portion PL2 b may besimultaneously removed by a fourth etching material inserted into thefirst trench TR1 and the first cavity CA1. The fourth etching materialmay be a material that is capable of etching the preliminary datastorage layer pDL and the second protective portion PL2 b of the secondprotective layer PL2. The second protective portion PL2 b of the secondprotective layer PL2 may be removed, and thus, the first protectiveportion PL2 a of the second protective layer PL2 may be exposed.

Referring to FIG. 3G, the portion of the preliminary tunnel insulatinglayer pTL (refer to FIG. 3F) that is exposed by the first cavity CA1 maybe removed. The portion of the preliminary tunnel insulating layer pTLmay be removed, and thus, the preliminary tunnel insulating layer pTLmay be divided into a first tunnel insulating layer TL1 and a secondtunnel insulating layer TL2. The portion of the preliminary tunnelinsulating layer pTL may be removed, and thus, a portion of the channellayer CL may be exposed.

The first protective portion PL2 a of the second protective layer PL2(refer to FIG. 3F) may be removed simultaneously with removing theportion of the preliminary tunnel insulating layer pTL or through aseparate process. For example, when the portion of the preliminarytunnel insulating layer pTL and the first protective portion PL2 a ofthe second protective layer PL2 are simultaneously removed, the portionof the preliminary tunnel insulating layer pTL and the first protectiveportion PL2 a of the second protective layer PL2 may be simultaneouslyremoved by a fifth etching material inserted into the first trench TR1and the first cavity CA1. The fifth etching material may be a materialthat is capable of etching the preliminary tunnel insulating layer pTLand the first protective portion PL2 a of the second protective layerPL2. The first protective portion PL2 a of the second protective layerPL2 may be removed, and thus, the third buffer patterns BP3, thesacrificial layers FL, and the third source layer SL3 may be exposed.

Referring to FIG. 3H, a preliminary source layer pSL may be formed inthe first cavity CA1 and the first trench TR1. The preliminary sourcelayer pSL may cover the third buffer patterns BP3, the sacrificiallayers FL, the third source layer SL3, and the first source layer SL1.The preliminary source layer pSL may contact the channel layer CL of thechannel structure CS.

Referring to FIG. 3I, a portion of the preliminary source layer pSL(refer to FIG. 3H) may be removed. The portion of the preliminary sourcelayer pSL covering the third buffer patterns BP3, the sacrificial layersFL, and the third source layer SL3 may be removed. The preliminarysource layer pSL from which the portion is removed may be defined as thesecond source layer SL2. A portion of the third source layer SL3 may beremoved together with the portion of the preliminary source layer pSL.

As the portion of the preliminary source layer pSL is removed, the firsttrench TR1 may be opened, and the sacrificial layers FL and the thirdbuffer patterns BP3 may be exposed again. As the portion of thepreliminary source layer pSL is removed, the second cavity CA2 may beformed in the source structure SOS.

Referring to FIG. 3J, the third buffer patterns BP3 and the sacrificiallayers FL may be removed. The third buffer patterns BP3 and thesacrificial layers FL may be simultaneously removed. The third bufferpatterns BP3 and the sacrificial layers FL may be removed by a sixthetching material inserted into the first trench TR1.

Referring to FIG. 3K, the conductive patterns CP may be formed in emptyspaces from which the sacrificial layers FL are removed. Subsequently,the spacers SP may be formed in the first trench TR1 and the secondcavity CA2. Subsequently, the source contact may be formed between thespacers SP.

In the method of manufacturing the semiconductor device, the secondprotective layer PL2 may protect the sacrificial layer FL of the stackstructure STA, the third buffer pattern BP3, and the third source layerSL3 in a process of removing the source sacrificial layer SFL, a processof removing a portion of the preliminary blocking layer pBKL, and aprocess of removing a portion of the preliminary data storage layer pDL.In addition, in a process of removing a portion of the preliminarytunnel insulating layer pTL, the third buffer pattern BP3 may protectthe insulating layer IL of the stack structure STA. The secondprotective layer PL2 may be removed in a process of removing a portionof the preliminary data storage layer pDL and a process of removing thepreliminary tunnel insulating layer pTL.

Accordingly, the preliminary source layer pSL may be formed in a statein which there is no separate layer covering the sidewalls of theinsulating layer IL and the sacrificial layer FL of the stack structureSTA, and thus, the width of the first trench TR1 may be designed to berelatively small. As the width of the first trench TR1 is designed to berelatively small, the degree of integration of the semiconductor devicemay be improved.

In addition, as the second cavity CA2 is formed in a state in whichthere is no separate layer covering the sidewalls of the insulatinglayer IL and the sacrificial layer FL of the stack structure STA, anover verify fail (OVF) based on the formation of the second cavity CA2may be prevented.

FIG. 4 is a block diagram illustrating a configuration of a memorysystem according to an embodiment of the present disclosure.

Referring to FIG. 4 , the memory system 1100 includes a memory device1120 and a memory controller 1110.

The memory device 1120 may include the structure described withreference to FIGS. 1A and 1B. The memory device 1120 may be a multi-chippackage configured of a plurality of flash memory chips.

The memory controller 1110 may be configured to control the memorydevice 1120, and may include a static random access memory (SRAM) 1111,a central processing unit (CPU) 1112, a host interface 1113, and anerror correction code (ECC) circuit 1114, and a memory interface 1115.The SRAM 1111 is used as an operation memory of the CPU 1112, the CPU1112 performs various control operations for exchanging data of thememory controller 1110, and the host interface 1113 includes a dataexchange protocol of a host that is connected to the memory system 1100.In addition, the ECC circuit 1114 detects and corrects an error includedin data read from the memory device 1120, and the memory interface 1115performs an interfacing with the memory device 1120. In addition, thememory controller 1110 may further include a read only memory (ROM) orthe like for storing code data for interfacing with the host.

The memory system 1100 described above may be a memory card or a solidstate disk (SSD) in which the memory device 1120 and the memorycontroller 1110 are combined to each other. For example, when the memorysystem 1100 is an SSD, the memory controller 1110 may communicate withthe outside (for example, the host) through at least one of variousinterface protocols such as a universal serial bus (USB), a multimediacard (MMC), a peripheral component interconnection-express (PCI-E), aserial advanced technology attachment (SATA), a parallel advancedtechnology attachment (PATA), a small computer system interface (SCSI),an enhanced small disk interface (ESDI), and integrated driveelectronics (IDE).

FIG. 5 is a block diagram illustrating a configuration of a computingsystem according to an embodiment of the present disclosure.

Referring to FIG. 5 , the computing system 1200 may include a CPU 1220,a random access memory (RAM) 1230, a user interface 1240, a modem 1250,and a memory system 1210, which are electrically connected to a systembus 1260. In addition, when the computing system 1200 is a mobiledevice, a battery for supplying an operation voltage to the computingsystem 1200 may be further included, and an application chipset, acamera image processor (CIP), a mobile DRAM, and the like may be furtherincluded.

The memory system 1210 may be configured of a memory device 1212 and amemory controller 1211 similar to those described with reference to FIG.4 .

What is claimed is:
 1. A semiconductor memory device comprising: a firstsource layer; a second source layer over the first source layer; a thirdsource layer over the second source layer; a stack structure including aplurality of insulating layers and a plurality of conductive patternsalternately stacked over the third source layer; an insulating spacer incontact with each of a portion of a top surface of the first sourcelayer exposed by the second source layer, a sidewall of the secondsource layer and a sidewall of the third source layer, the insulatingspacer extending along a sidewall of the stack structure; a channellayer disposed in the stack structure and extending in the first sourcelayer, wherein a portion of the second source layer is in contact withthe channel layer; and a memory layer disposed between the channel layerand each of the stack structure, the first source layer and the thirdsource layer, wherein an interface between the insulating spacer and thesecond source layer is further away from the channel layer as theinterface is closer to the third source layer.
 2. The semiconductordevice of claim 1, wherein the interface between the insulating spacerand the second source layer has a round shape.
 3. The semiconductordevice of claim 1, wherein an interface between the insulating spacerand the third source layer is further away from the channel layer as theinterface is closer to the stack structure.
 4. The semiconductor deviceof claim 3, wherein the interface between the insulating spacer and thethird source layer has a round shape.
 5. The semiconductor device ofclaim 1, wherein the portion of the top surface of the first sourcelayer exposed by the second source layer has a round concave shape. 6.The semiconductor device of claim 1, further comprising: a conductivesource contact extending along a sidewall of the insulating spacer,wherein the conductive source contact is in contact with the portion ofthe top surface of the first source layer exposed by the second sourcelayer.
 7. The semiconductor device of claim 6, wherein the insulatingspacer is disposed between the stack structure and the conductive sourcecontact.
 8. A method of manufacturing a semiconductor memory device, themethod comprising: forming a preliminary source structure including afirst source layer, a source sacrificial layer over the first sourcelayer and a second source layer over the source sacrificial layer;forming a hole in the preliminary source structure; forming apreliminary memory layer on a surface of the hole; forming a channellayer in the hole, wherein the channel layer is disposed on thepreliminary memory layer; forming a trench penetrating the second sourcelayer; forming a protective layer on a sidewall of the trench; forming acavity exposing a portion of the preliminary memory layer by removingthe source sacrificial layer in a state that the second source layer isprotected by the protective layer; forming an expanded cavity exposing aportion of the channel layer by removing the portion of the preliminarymemory layer exposed by the cavity; removing the protective layer toexpose the second source layer; and forming a third source layer in theexpanded cavity to be in contact with the portion of the channel layerexposed by the expanded cavity after removing the protective layer. 9.The method of claim 8, wherein the source sacrificial layer includes amaterial with an etching selectivity with respective to oxide.
 10. Themethod of claim 8, further comprising: forming a buffer pattern byperforming a surface treatment of a sidewall of the second source layerthrough the trench; and removing the buffer pattern between the formingof the expanded cavity and the forming of the third source layer. 11.The method of claim 10, wherein the protective layer covers the bufferpattern.
 12. The method of claim 8, further comprising: forming a stackstructure by alternately stacking a plurality of first material layersand a plurality of second material layers over the preliminary sourcestructure, wherein the hole, the preliminary memory layer and thechannel layer extend in the stack structure, and wherein the trenchpenetrates the stack structure.
 13. The method of claim 12, furthercomprising: forming plurality of buffer patterns by performing a surfacetreatment of a sidewall of the plurality of second material layersthrough the trench; removing the plurality of buffer patterns betweenthe forming of the expanded cavity and the forming of the third sourcelayer; and replacing the plurality of second material layers with aplurality of conductive patterns through the trench after forming of thethird source layer.
 14. The method of claim 12, further comprising:forming plurality of buffer patterns by performing a surface treatmentof a sidewall of the plurality of first material layers through thetrench; removing the plurality of buffer patterns after the forming ofthe third source layer; and replacing the plurality of second materiallayers with a plurality of conductive patterns through the trench.